Ice will not sustain major deviations in thickness for long spans of time, but I think the critical issue is if it can sustain them for a short time. Either a rift or a hot spot (which could mean a plume of slushy ice, or actually water welling up to or near the surface). I think the whole ballgame with Europa is to see if there's a place like that. If so, a submarine is possible. If not, we're stuck with the top few meters to explore.

I think the dark lineation along the triple bands is an indication that water gushed out along a huge number of tremendously long faults. Given the surface age of Europa, that translates into a considerable amount of active fault per year. The trick is whether you get about that much fault all the time, or if you have none at a typical moment, then occasionally much more activity takes place.

But we don't need an actual gusher -- just a place where the 20 km depth has been considerably reduced.

Incidentally, I think on the first one, they got the apparent motion of Jupiter completely backwards while moreover depicting Jupiter as tidally locked WRT the Sun (or somehow otherwise rotating other than the way it actually does).

The goal was for Jupiter's rotation not to distract from the message, so Jupiter was not rotating at all. Riding along with Europa but with Jupiter not rotating unfortunately gave the false impression that Jupiter was rotating backwards.

Probably for most people it didn't. But I'm the kind of guy who whispers to the person next to me in the movie theatre if the sun appears too high in the sky for the latitude and season that a scene is set in, or if the sun is on the left of someone who is supposedly driving east in the northern hemisphere. I'm glad that for one, my pedantry had an impact!

NASA will host a Science Update at 1 p.m. EST on Wednesday, Nov. 16, to discuss new theories concerning Jupiter's icy moon Europa. The event will be in NASA's James E. Webb Auditorium at 300 E St. SW in Washington.

NASA Television and the agency's website will broadcast the event live. Reporters may attend the event or ask questions from participating NASA centers or by phone. For dial-in information, reporters must contact Dwayne Brown at: dwayne.c.brown@nasa.gov with their name, media affiliation and telephone number by noon Wednesday.

Europa, which is slightly smaller than Earth's moon, is thought to have an iron core, a rocky mantle and an ocean of salty water beneath its frozen surface.

Getting at the ice shell thickness has been a real problem. All our evidence is circumstantial. But there are mountains a kilometerhigh andbasins a kilometer deep. the surface is warped and the craters need to get very large before they start to penetrate near the bottom.all these things point to a thicker ice shell, likely a minimum of 10 km, possibly as much as 20 km.

Really is a conundrum... to me. I just wonder how you get enough energy from warm (hot) water plumes in the underlying ocean to penetrate through kilometers of steel hard ice. Yet the topography demands a thick ice shell.

agreed. the new model and even the diapir model rely on warm ice from the base of the shell rising upward in a dome, like porridge boiling on a stove. water plumes melting through this thick ice is very difficult indeed, but doing it within the shell, thats easy(ier)

So we are still talking plumes of warm ice... even in this new model. Yet the matrix looks like it needs melted ice (water) to explain the chaos. I am probably missing something. Are we talking a mechanism that lets melt (water) migrate to the top? Guess I really need to read the paper!

its a difficult concept even for me, but the rising plume changes the conditions of the ice over it. melting is a function of pressure as well as Temp,and this causes a zone of ice to melt over the plume. yes it all takes place within the shell itself

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